1. Field of the Invention
This invention relates to a gelatin capsule formulation that provides a brittle shell that can be manually broken for the release of the contents therein. More particularly, it relates to a gelatin capsule formulation that utilizes a non-hygroscopic plasticizer to plasticize the gelatin in the formulation to provide a shell that after drying resists moisture and remains brittle but that is strong enough to be manufactured in a traditional rotary die encapsulation device.
2. Brief Description of the Prior Art
Breakable capsules were developed in the 1940's for the purpose of delivering yellow dye to add coloring to margarine so it would look similar to butter. The breakable capsule was produced by using a glycerine plasticized gelatin capsule that was treated with formaldehyde to cross link the gelatin. Other agents are used to harden the gelatin to provide the moisture resistance and be brittle so as to allow breaking of the capsule.
U.S. Pat. No. 4,055,554 discloses the use of chemically modified dialdehyde polysaccharides to enhance the strength of the gelatin compositions used to produce capsules which have been extended with starch or dextrin.
U.S. Pat. No. 4,350,679 discloses a coating of film of carnauba wax on a soft gelatin capsule to provide strength to the capsule shell. The carnauba wax inhibits the absorption of water into the shell formulation and thus provides moisture resistance to the shell.
U.S. Pat. No. 3,592,945 discloses a protective coating on gelatin capsules comprising a copolymer of methacrylic acid and methylmethacrylate having a molecular weight between 110,000 and 160,000. A softener such as dibutyphthalate and castor oil may be added.
When capsules are coated or chemically treated, the ease of manufacture is reduced and costs increase. There is a need for a gelatin capsule that has enough strength to hold liquid filling material and withstand the manufacturing process on a conventional rotary die capsule making device but that after drying is brittle and can be easily broken open manually to release the contents therein.